return it == objects_by_id_.end() ? nullptr : it->second;
  }

 private:
  std::vector<std::unique_ptr<T>> objects_;
  absl::flat_hash_map<int, T*> objects_by_id_;
};

// RevivedObjects is mainly used as a container for all the "state" owned by
// SavedModel. It stores all non-"user object" nodes from a SavedModel

                                         const SavedObjectGraph& obj_graph,
                                         const PartiallyRevivedObjects& objects,
                                         RevivedObjects* revived) {
  for (const auto& id_and_resource : objects.restored_resources) {
    const RestoredResourceRevivalState& resource = id_and_resource.second;
    const TFConcreteFunctionRevivalState* create_resource_fn =

  SavedModelV2Bundle* GetBundle() override;

 private:
  TFSavedModelAPI(const std::string& directory, SavedModelV2Bundle bundle,
                  RevivedObjects revived_objects);

  std::string directory_;
  SavedModelV2Bundle bundle_;
  RevivedObjects revived_objects_;
};

}  // namespace tensorflow

 public:
  // Note(bmzhao): RestoredResource stores non-owning pointers to its associated
  // functions because SavedModel internally owns all functions and objects in
  // the RevivedObjects struct (which owns all functions). One alternative would
  // be to have RevivedObjects store shared_ptr<TFConcreteFunction> instead, and
  // change RestoredResource's constructor take shared_ptr<TFConcreteFunction>.

// https://github.com/tensorflow/tensorflow/blob/ddc1bbad3dfd4a089eb96014f26cc16664b1b2f8/tensorflow/python/training/saving/saveable_object.py#L85
Status RestoreCheckpoint(SavedModelV2Bundle* bundle,
                         const RevivedObjects& revived_objects,
                         const std::string& directory,
                         ImmediateExecutionContext* context) {
  // TODO(bmzhao): Batch up all the restores into a single restore op per

  gtl::FlatMap<int, RestoredResourceRevivalState> restored_resources;
  gtl::FlatMap<std::string, int> signatures_map;

  Status Build(ImmediateExecutionContext* ctx,
               const SavedObjectGraph& obj_graph, RevivedObjects* revived);
};

}  // namespace tensorflow